盐生植物盐爪爪的耐盐生理特性探讨

Physiological characteristics of the halophytic plant Kalidium foliatum to salt stress

关键词:  盐生植物  盐爪爪  耐盐生理

Key words:  halophyte  Kalidium foliatum  salt-tolerant physiology

摘要:

当前土壤盐渍化日益严重,是限制植物生长的一个主要环境因子,然而在盐碱自然环境中生长着许多耐盐植物,为更好地了解盐生植物的耐盐机理,该文从无机离子Na⁺,K⁺,Ca²⁺含量、脯氨酸水平、水势变化、丙二醛含量和盐胁迫的表型等生理参数以及半定量RT-PCR检测脯氨酸合成关键酶基因(P5CS)的表达规律等方面探讨盐胁迫下盐爪爪的耐盐特性。结果表明:(1)随着盐浓度的升高,Na⁺在根和肉质化的叶中显著地富集,且叶中积累的Na⁺ 比根中更多;(2)在盐胁迫条件下,随着盐浓度的增加,脯氨酸的含量和脯氨酸合成关键酶基因的表达显著地增强;(3)Na⁺和脯氨酸是植物有效的渗透调节剂,可使处于低水势的植物细胞仍能从细胞外高浓度的盐溶液中吸收水分;(4)在0和700 mmol·L^-1 NaCl处理下,盐爪爪肉质化叶中丙二醛的含量较其它处理高,这表明植物在这两个处理下可能受到了氧化胁迫;(5)从盐胁迫3个月的生长表型来看,低盐环境中生长的盐爪爪植株的生物量更多,肉质化的叶嫩且绿。综上所述,结合对野外生境的调查和实验室长期的盐胁迫表型结果表明盐爪爪的生长是需盐的,相对低的盐浓度环境对盐爪爪的生长是顺境,而无盐或高浓度盐环境对于盐爪爪的生长来说都是逆境。该研究结果为全面深入研究盐爪爪的耐盐特性,以及更好地利用盐爪爪的生物和基因资源改良土壤和提高作物和林木的耐盐性奠定基础。

Abstract:

At present, more and more serious soil salinization is one of the main environmental factors that limit plant growth and crop yield. Many halophilous plants often grow in the saline-alkaline land. In order to better understand the salt tolerant mechanism of halophytic plants,this paper mainly explored some physiological characteristics of the halophytic plant Kalidium foliatum to salt stress according to some physiological indexes. The halophyte K. foliatum is a kind of very salt-tolerant shrub belonging to Chenopodiaceae with high succulence and grows commonly in saline and alkaline arid-desert regions in Xinjiang. Some physiological parameters were detected including the contents of Na⁺,K⁺,Ca²⁺ and proline,the water potential of plant leaf tissue, the content of membrane lipid peroxidation(MDA)and phenotype observation; gene expression of KfP5CS,encoding protein(pyrroline-5-carboxylate synthetase)as a key enzyme catalyzing to synthesize proline by semi-quantitative RT-PCR were assayed to salt stress. The results were as follows:(1)Na⁺ could accumulate significantly in succulent leaves and roots of K. foliatum,and even the content of Na⁺ in leaves was more than roots;(2)With increasing salt concentration,the content of proline and the gene expression of KfP5CS were enhanced significantly under salt stress conditions;(3)Na⁺ and proline as plant effective osmotic regulators, could make the plant cells be still able to absorb water at low water potential from the highly concentrated salt solution,extracellularly;(4)Under 0 and 700 mmol·L^-1 NaCl treatments, the contents of MDA in the leaves of K. foliatum were higher than other salt treatments, suggesting that the plants might be subjected to oxidative stress under the both treatments. This phenomenon indicated that the growth environments with the both treatments might be adverse for the plants;(5)From the growth phenotype to salt stress, the biomass of K. foliatum was more under low salt treatments, and the plant growth was better and stronger, indicating the low salt environment seemed to be beneficial to the K. foliatum growth. In summary, the results of the investigation of the K. foliatum plant growth in wild grown environment and under long-term salt stress in our lab showed that it was necessary for the good growth of K. foliatum in a certain salt concentration condition. A relative low salt concentration environment is very optimal for the growth of some very salt-tolerant halophytes like K. foliatum. However, we can also speculate neither salt nor high concentration salt conditions is the stressed environment for the K. foliatum plant growth. The study could provide primary reference for understanding the salt tolerance of K. foliatum and it is also very promising to improve salt tolerance in crops and woods by making use of gene resources of this species and the halophyte K. foliatum could be also used to ameliorate saline-alkaline land by reducing the salt content of soil.